Talk:Quantum phase transition

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What does "Such quantum phase transitions can be phase transition or continuous" mean? I guess it is a typo. What should it say?

what is so "quantum" about a QPT?

I fail to see in what sense quantum effects are relevant for a QPT. Take a classical antiferromagnetic spin lattice, for example: why shouldn't there be a zero temperature phase transition when the external magnetic field is varied? There is a well-defined (possibly degenerate) classical ground state, and its energy might change in a non-analytic way under variation of the magnetic field.

Also, the statement "A classical system does not have entropy at zero temperature" also applies in the quantum case since a pure state has vanishing entropy. - Saibod 11:05, 31 August 2007 (UTC)[reply]

I don't know if the term is appropriate, but......

Biological quantum transition

http://scholar.google.com.hk/scholar?start=0&q=allintitle:+biological+quantum+transition&hl=en&as_sdt=2000

--222.64.212.180 (talk) 01:38, 5 August 2010 (UTC)[reply]

Don't know if the topic of.....

Quantum interference can be auto-directed

http://scholar.google.com.hk/scholar?as_q=quantum+interference&num=10&btnG=Search+Scholar&as_epq=&as_oq=&as_eq=&as_occt=title&as_sauthors=&as_publication=&as_ylo=&as_yhi=&as_sdt=1.&as_sdtp=on&as_sdts=5&hl=en

--222.64.212.180 (talk) 01:48, 5 August 2010 (UTC)[reply]

Info about the topic of......

Quantum invasion

http://scholar.google.com.hk/scholar?as_q=quantum+invasion&num=10&btnG=Search+Scholar&as_epq=&as_oq=&as_eq=&as_occt=title&as_sauthors=&as_publication=&as_ylo=&as_yhi=&as_sdt=1.&as_sdtp=on&as_sdts=5&hl=en

--222.64.212.180 (talk) 01:52, 5 August 2010 (UTC)[reply]

Info about the topic of ......

Quantum spirituality

--222.64.212.180 (talk) 02:11, 5 August 2010 (UTC)[reply]

Info about the topic of .....

Quantum ghost and soul

http://scholar.google.com.au/scholar?hl=en&q=allintitle%3A+%22quantum+ghost%22&btnG=Search&as_sdt=2000&as_ylo=&as_vis=0

--222.64.212.180 (talk) 02:14, 5 August 2010 (UTC)[reply]

http://scholar.google.com.au/scholar?hl=en&q=allintitle%3A+quantum+soul&btnG=Search&as_sdt=2000&as_ylo=&as_vis=0

--222.64.212.180 (talk) 02:16, 5 August 2010 (UTC)[reply]

Is it mistaken by the sign > ?

It says "For \hbar \omega > k_{B}T, quantum fluctuations will dominate the system's properties." But intuitively, if k_{B}T is smaller, then thermo-excitation can be more easily excited and thus play a role in the physical properties. So I would think that there the > sign should be replaced with < sign. But then, another question kicks in. It is later mentioned that "ω is the characteristic frequency of a quantum oscillation and inversely proportional to the correlation time.", which means small ω implies longer correlation time, and thus presumably, longer correlation length as well. Under very low or even vanishing temperature, what is the energy source to lead to such wide range collective motions, which could be infinite as the system becomes in thermodynamic limit?